GOSSEA SPENCE BATE & WESTWOOD, 1862 (AMPHIPODA) AND GOSSEA AGASSIZ, 1862 (CNIDARIA, HYDROZOA): REVERSAL OF PRESUMED PRECEDENCE AND REVIEW OF THE COMPLICATED NOMENCLATURAL HISTORY

Gossea Agassiz, 1862 (Cnidaria: Hydrozoa) and Gossea Spence Bate & Westwood, 1862 (Crustacea: Amphipoda) are homonyms and Agassiz’s genus has long been considered the senior name. Discovery of copyright information for Agassiz’s book shows that the presumed order of precedence is incorrect and that Spence Bate & Westwood’s genus name is the senior homonym. A detailed history of both genera is given with the recognition that Apherusa Walker, 1891 is an unnecessary replacement name for Gossea Spence Bate & Westwood, 1862 and that Octobulbacea Zamponi, 1983, as the only available junior synonym, is the name that should be used for Gossea Agassiz, 1862.

The generic name Gossea Agassiz, 1862 (Cnidaria: Hydrozoa) has been considered a senior homonym of Gossea Spence Bate & Westwood, 1862 (Crustacea: Amphipoda) since Walker (1892) recognized that Gossea microdeutopa Spence Bate & Westwood, 1862 was a junior subjective synonym of Apherusa jurinii [sic] (H. Milne Edwards, 1830). Walker (1892) noted that both Gossea names were published in the same year and stated that it was "obviously more convenient that Agassiz's genus should be retained" which meant that Apherusa Walker, 1891b was, in Walker's opinion, the correct name for the amphipod genus. It may have been more convenient for Walker to maintain the usage of his own name, but this contravenes the ICZN's principle of priority (ICZN, 1999: Article 23 fig. 6) names as new, but used the spelling microdentopa on the plate, which is herein considered to be an incorrect subsequent spelling sensu ICZN (1999: Art. 33.3). Gossea and G. microdeutopa were thus both validly published in volume I, part 6 of "A History of British Sessile-Eyed Crustacea in Two Volumes" with part 6 published on 1 April 1862 fide Holthuis (1977).
Walker (1891a) discussed the confusion around the identity of Pherusa fucicola Leach, 1814 (currently Gammarella fucicola (Leach, 1814)) and synonymized Pherusa with Gammarella Spence Bate, 1857 but incorrectly continued to consider Pherusa as a valid genus credited to "Bate, 1862". Pherusa Leach, 1814 is a junior homonym of Pherusa Oken, 1807 (Annelida: Polychaeta) but this was not recognized by Walker (1891a); Gammarella being an available junior synonym of Pherusa Leach, it is the name currently in use as valid.
Walker (1891b) subsequently concluded that he could not use "Bate's genus Pherusa, 1862" because it was not identical with that of Leach, 1814, that it was not "Bate's genus" but rather Pherusa sensu Spence Bate, "1862" (actually 1863, see below). Walker then introduced the name Apherusa for Pherusa sensu Spence Bate, "1862" non Leach, 1814. The type species of Apherusa is Ampithoe jurinei H. Milne Edwards, 1830 by monotypy as only a single species was included by Walker (1891a) in his concept of Pherusa sensu Bate non Leach, 1814 and this was the concept alluded to in Walker (1891a) when he replaced Pherusa sensu Bate with Apherusa as a new name.
Walker (1892) re-examined three type specimens of Gossea microdeutopa (all in poor condition) and concluded that they represented the same species identified by Spence Bate (1863) as both Pherusa fucicola (pp. 145-146; misidentification) and Gossea microdeutopa (pp. 159-160; listed as new genus and species) and that both were synonyms of Apherusa jurinii [sic]. Walker (1892) cited Spence Bate (1863) as the source of these names although they were first published in Spence Bate & Westwood (1862: 255 and 276-278, respectively). Other than that Walker may have been unaware that "A History of British Sessile-Eyed Crustacea in Two Volumes" was published in parts (see Holthuis, 1977), Gossea microdeutopa was labeled as being a new genus and species only in Spence Bate (1863), which was clearly intended to come out before Spence Bate & Westwood (1862) as the relevant page numbers in the 1862 paper were cited in the 1863 work (see De Grave & Boyko, unpubl. data). Walker (1892) retained Apherusa as the name for the amphipod genus because he thought that Spence Bate (1863; see Sherborn, 1934) was published first in 1862 in advance of Spence Bate & Westwood's work and that Gossea Spence Bate was a junior homonym of Gossea Agassiz (see below).
Agassiz (1862) erected Gossea as a new genus for "Thaumantias? Corynetes" Gosse, 1853, this being type species by monotypy. No characters were given for the genus but as it is a pre-1931 name, this is permissible (ICZN, 1999: Article 12.2) and the name is available. The date of copyright of Agassiz's book was 28 May 1862 and a copy of the book was not deposited in the District Clerk's of Massachusetts office until 13 August 1862 ( fig. 1). The book, therefore, cannot have been published before 28 May 1862 and most likely was published closer to 13 August 1862.
Recognizing that Spence Bate & Westwood's (1862) publication predates Spence Bate (1863) makes no functional difference as Gossea was indeed used as a new genus name twice in 1862 and the publication date of 1 April 1862 for the amphipod genus name predates the 28 May 1862 copyright date (and likely much later publication date) for the cnidarian. Therefore, Gossea Spence Bate & Westwood (1862) is the senior homonym of Gossea Agassiz (1862) rather than the reverse, and the latter name needs to be replaced.